1. Field of the Invention
The present invention relates to a pneumatic tire with an excellent ride feeling in which harshness and road noise problems are effectively and appropriately solved.
2. Related Art Statement
In order to improve the ride feeling against vibrations of the pneumatic radial tires for use in passenger cars, it is necessary to take countermeasures against the so-called harshness ordinarily peculiar in the case of the vibration frequently of not more than 100 Hz at a speed of 20-60 km and vehicle inside noises at around 80 to 300 Hz produced in running on irregularly uneven roads such as roughly paved roads at a vehicle speed of 30 to 80 km/h, that is, the so-called road noises.
Although passenger car pneumatic tires have a tread which is reinforced by a belt composed of metal cord layers piled so that the cords are intersected with one another to have a smaller rolling resistance and more excellent cornering stability as compared with the tires using textile cords in the belt, it is known that the former type of tires do not necessarily give satisfactory ride feeling.
To the contrary, the harshness including vertical and forward and rearward axial movement forces when the tire rides over projections on a road is reduced by using organic cord layer or a cap belt layer in combination with the metal cord belt layers and restraining enveloping at the tread. Thereby, vibrations of not more than 100 Hz are reduced particularly in a vehicle speed range from 20 to 60 km/h. With respect to the road noises at frequency range of not less than 100 Hz, this countermeasure can afford some effect.
However, while the rigidity against bending outside of the belt plane is increased by reinforcing the belt with such an organic cord layer or cap belt layer, there are disadvantages that the tire weight increases and in addition the rolling resistance is extremely deteriorated.